Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$107.95	10.826%	$119.6367	$119.64	$119.65	$119.60
Purchase #2	$127.69	10.840%	$141.5316	$141.53	$141.55	$141.50
Purchase #3	$171.82	8.863%	$187.0484	$187.05	$187.05	$187.00
Purchase #4	$180.90	5.324%	$190.5311	$190.53	$190.55	$190.50
Purchase #5	$137.45	12.806%	$155.0518	$155.05	$155.05	$155.10
Purchase #6	$189.88	11.124%	$211.0023	$211.00	$211.00	$211.00
Purchase #7	$158.41	6.134%	$168.1269	$168.13	$168.15	$168.10
7 purchase totals =	$1,074.10		$1,172.9288	$1,172.93	$1,173.00	$1,172.80